1. Field of the Invention
The present invention relates to a storage medium having a breath detection program stored therein and a breath detection apparatus, and more particularly to a storage medium having stored therein a breath detection program used for, for example, detecting a sound inputted into a sound input device, and a breath detection apparatus.
2. Description of the Background Art
Conventionally, as disclosed in, for example, Japanese Laid-Open Patent Publication No. 2006-145851 (hereinafter, referred to as Patent Document 1), a game apparatus is known which detects an inputted sound based on a frequency distribution by analyzing waveform data of the inputted sound. For example, the game apparatus disclosed in Patent Document 1 analyzes waveform data of the inputted sound to calculate zero cross time intervals each of which represents a time interval between two zero cross points and acquire a frequency distribution represented by the waveform data, based on the calculated zero cross time intervals. Whether or not the inputted sound represents a user's breath is determined based on whether or not the obtained frequency distribution satisfies a predetermined criterion.
However, in general, in a case where a user continues to blow a breath into a sound input device such as a microphone, even when the breath of the constant level continues to be blown, the intensity of the breath tends to be gradually reduced. Therefore, in the game apparatus disclosed in Patent Document 1, it is difficult to set a criterion for detecting whether or not a sound being inputted is caused by the breath, throughout the whole period in which the breath continues to be blown. For example, in a case where the criterion for detecting for a breath is set relatively strict such that the starting of the breath blowing can be detected, even when the breath continues to be blown, the breath may not be detected when some time elapses after the starting of the breath blowing. On the other hand, in the game apparatus disclosed in Patent Document 1, in a case where the criterion for detecting for a breath is set relatively loose, even when a user is not blowing a breath, an input, other than a breath, to the sound input device, that is, a noise, an ambient sound, or the like, may be detected as a breath.